A new specific and sensitive time resolved-fluoroimmunoassay of 11-deoxycortisol in serum

A biotinylated 11-deoxycortisol tracer was synthesized from 11-deoxycortiso l-3-carboxymethyloxime and the conjugate obtained by acylation of biotinyla minopropylammonium trifluoroacetate, This biotinylated tracer was used to d evelop an 11-deoxycortisol time-resolved-fluoroimmunoassay (TR-FIA). The tr acer was quantified after adding strsptavidine-Europium. A TR-FIA sensitive standard curve. with displacement of 20, 50. and 80% of tracer was obtaine d with 12.4. 70.7, and 512.8 pg of 11-deoxycortisol, respectively. After ex traction followed by Celite chromatography. purified serum samples were sim ultaneously assayed by RIA and TR-FIA. The results obtained by the two meth ods were practically identical, however, this new specific. non-isotopic 11 -deoxycortisol assay has the advantage of being more sensitive than RIA, th us well-suited to accurate measurement in endocrinological studies, particu larly when serum 11-deoxycortisol levels in patients are just above the hig hest normal values. Moreover, this non-isotopic assay is cheaper than RIA. (C) 2001 Elsevier Science Ltd. All rights reserved.